• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.229-235
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• 2013

In this paper, we investigate several important issues on the implementation of a totally implantable microsystem for brain-machine interface that has been attracting a lot of attention recently. So far most of the scientific research has been focused on the high performance, low power electronics or systems such as neural signal amplifiers and wireless signal transmitters, but the real application of the implantable microsystem is affected significantly by a number of factors, ranging from design of the encapsulation structure to physiological and anatomical characteristics of the brain. In this work, we discuss on the thermal effect of the system, the detecting volume of the neural probes, wireless data transmission and power delivery, and physiological and anatomical factors that are critically important for the actual implementation of a totally brain implantable neural interface microsystem.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.223-227
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• 2003

A new flexible electronic packaging technology and its medical applications are presented. Conventional silicon chips and electronic modules can be considered as "mechanically rigid box." which does not bend due to external forces. This mechanically rigid characteristic prohibits its applications to wearable systems or bio-implantable devices. Using current MEMS (Microelectromechanical Systems) technology. a surface micromachined flexible polysilicon sensor array and flexible electrode array fer neural interface were fabricated. A chemical thinning technique has been developed to realize flexible silicon chip. To combine these techniques will result in a realization of truly flexible sensing modules. which are suitable for many medical applications.

• Electronics and Telecommunications Trends
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• v.33 no.6
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• pp.69-80
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• 2018

Sensory devices have been developed to help people with disabled or weakened sensory functions. Such devices play a role in collecting and transferring data for the five senses (vision, sound, smell, taste, and tactility) and also stimulating nerves. To provide brain or prosthesis devices with more sophisticated senses, hyper sensory devices with a high resolution comparable to or even better than the human system based on individual neuron cells are essential. As for data collecting components, technologies for sensors with higher resolution and sensitivity, and the conversion of algorithms from physical sensing data to human neuron signals, are needed. Converted data can be transferred to neurons that are responsible for human senses through communication with high security, and neural interfaces with high resolution. When communication deals with human data, security is the most important consideration, and intra-body communication is expected to be a candidate with high priority. To generate sophisticated human senses by modulating neurons, neural interfaces should modulate individual neurons, and therefore a high resolution compared to human neurons (~ several tens of um) with a large area covering neuron cells for human senses (~ several tens of mm) should be developed. The technological challenges for developing sensory devices with human and even beyond-human capabilities have been tackled by various research groups, the details of which are described in this paper.

• Journal of Biomedical Engineering Research
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• v.30 no.4
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• pp.347-354
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• 2009

For the reliable transmission of meaningful visual information using prosthetic electrical stimulation, it is required to develop an effective stimulation strategy for the generation of electrical pulse trains based on input visual information. The characteristics of neuronal activities of retinal ganglion cells (RGCs) evoked by electrical stimulation should be understood for this purpose. In this study, for the development of an optimal stimulation strategy for visual prosthesis, we analyzed the neuronal responses of RGCs in rd1 mouse, photoreceptor-degenerated retina of animal model of retinal diseases (retinitis pigmentosa). Based on the in-vitro model of epiretinal prosthesis which consists of planar multielectrode array (MEA) and retinal patch, we recorded and analyzed multiunit RGC activities evoked by amplitude-modulated electrical pulse trains. Two modes of responses were observed. Short-latency responses occurring at 3 ms after the stimulation were estimated to be from direct stimulation of RGCs. Long-latency responses were also observed mainly at 2 - 100 ms after stimulation and showed rhythmic firing with same frequency as the oscillatory background field potential. The long-latency responses could be modulated by pulse amplitude and duration. From the results, we expect that optimal stimulation conditions such as pulse amplitude and pulse duration can be determined for the successful transmission of visual information by electrical stimulation.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1243-1244
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• 2015

Finding solutions for the disabled is a major challenge for our society. In the case of a disability due to a malfunction of the nervous system, the origin may be accidental, genetic, or induced by environmental factors. This type of loss can cause loss or movement disorders (paraplegia, hemiplegia, quadriplegia, epilepsy, Parkinson's disease, multiple sclerosis, etc.) or malfunction of certain sensory functions (blindness, deafness, chronic pain, etc.). Many alternatives, more technology, have been imported to create interfaces between the human body and an artificial prosthesis in order to restore some functions of the human body. A wireless system, battery neurons probe was developed for one hand reading neural signals in the brain, and on the other hand also able to excite the neuron in the brain using a surface acoustic wave one ports (SAW) delay line reflection.

• Journal of Biomedical Engineering Research
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• v.29 no.6
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• pp.415-430
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• 2008

The technologies in medical electronic implant(MEI) devices are developing rapidly, and already, there are various kinds of the MEI devices in the current medical equipments market. Recently, the global market scale of MEI devices have been increased about 13% year by year, and the import amount of MEI devices in Korea is increasing rapidly. In the near future, the demands of MEI devices will be magnificently increasing by the continuous development of the biomedical electronics devices which coupled with neural, brain and other organs will bring us to tremendous effects, such as providing new therapeutic solutions to patients, extension and saving human life, and an important clue of medical development. However, the investment of the research and the activity of developments in this field are still very weak in the Korea. Consequently, this paper introduces about the research trends of MEI devices, and technological problems those must be solved, and then concludes with the suggestions in order to be the leading country in this field.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.35-41
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• 2017

We propose a novel multi-photodiode array (MPDA) based retinal implant IC with on/off stimulation strategy for a visual prosthesis with improved spatial resolution. An active pixel sensor combined with a comparator enables generation of biphasic current pulses when light intensity meets a threshold condition. The threshold is tuned by changing the discharging time of the active pixel sensor for various light intensity environments. A prototype of the 30-channel retinal implant IC was fabricated with a unit pixel area of $0.021mm^2$, and the stimulus level up to $354{\mu}A$ was measured with the threshold ranging from 400 lx to 13120 lx.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.14 no.1
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• pp.5-9
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• 2003

Introduction : Laryngomicrosurgery(LMS) is frequent procedure applying to benign and early malignant larygeal disease such as vocal cord polyp, nodule and early glottic cancer. LMS has been known as safe procedure and short time consuming treatment. So few reports about complications in LMS was done. In this study, complications and problems from LMS were investigated and reported. Method : From 2000, January to 2001, December, 180 patients who were treated with LMS in Asan medical center were studied by retrograde chart review. Results : In these patients, total 9 patients(5%) were suffered from complication. 4 patients (2%) had teeth injury and 4(2%) were suffered from foreign body sensation in tongue and 1(1%) had hypoglossal nerve injury. Main mechanism of complications is thought by pressure injury by laryngoscope blade. No definite correlation between procedure and complication was observed. Conclusion : There are few neural complications with LMS such as lingual and hypoglossal nerve injury. Before operation of LMS, warning and informing of complications by mechanical stress must be done. Gentle procedure and short operation time are necessary to avoid these problems. And patients who have risk factors of oral complications such as dental disease or dental prosthesis must have dental evaluation and treatment before LMS procedure.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.287-293
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• 2013

Cochlear implant (CI) is an auditory prosthesis that delivers electrical stimulation via inserted electrodes into a cochlea. To evaluate CI performance, it is important to understand how auditory nerves are responded to electrical stimulations. In clinic, electrically evoked compound action potential (ECAP) is measured. In this study, we developed 3D finite element (FE) cochlear model to simulate ECAP in response to electrical stimulation. The model prododuced ECAP similar to that measured in animal experiments and clinics. This 3D FE cochlear model could be used in electrical stimulus method study to improve CI by analyzing neural responses to electrical stimulations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2143-2149
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• 2007

Visual Cortex Stimulator is among artificial retina prosthesis for blind man, is the method that stimulate the brain cell directly without processing the information from retina to visual cortex. In this paper, we propose image construction and recognition model that is similar to human visual processing by recognizing the feature data with orientation information, that is, the characteristics of visual cortex. Back propagation algorithm based on Delta-bar delta is used to recognize after extracting image feature by Kirsh edge detector. Various numerical patterns are used to analyze the performance of proposed method. In experiment, the proposed recognition model to extract image characteristics with the orientation of information from retinal cells to visual cortex makes a little difference in a recognition rate but shows that it is not sensitive in a variety of learning rates similar to human vision system.